Abstract
This paper presents the new data on thermodynamic properties of hydrous iron phosphate, vivianite. The thermochemical study of natural vivianite Fe2.322+Fe0.333+ Mg0.35(PO4)2(OH)0.33·7.67H2O (Kerch iron ore basin, Republic of Crimea, Russia) was carried out on a high-temperature heat-flux Tian-Calvet microcalorimeter “Setaram” (France). The mineral was characterized by X-ray microprobe analysis, powder and single-crystal X-ray diffraction, thermal analysis, FTIR, Raman and Mössbauer spectroscopy. The value of ΔfHm0(T=298.15K) for natural vivianite was found to be −(5217±11kJmol−1). The standard values of the entropy, enthalpy and Gibbs energy of formation at T=298.15K for vivianite of theoretical composition Fe32+(PO4)2·8H2O were calculated as (571.0)J(Kmol)−1, −(5119±19)kJmol−1 and −(4439±19)kJmol−1 respectively.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
